Abstract: Phased array ultrasonic and digital Ray detection technology is a new type of nondestructive detection method developed by computer imaging technology in recent years. It can make up for the deficiency of conventional ultrasonic and Ray film detection technology and has good application prospects. In this paper, by making simulated samples of water-cooled wall welds, the phased array ultrasonic and digital Ray detection technology were used to detect precast defects.The feasibility of testing is verified through analyzing the technical characteristics, which provides a new idea for the future non-destructive testing of water-cooled wall welds.